The purpose of the Biostatistics Core is to provide professional expertise in statistics for all Vanderbilt University Breast Cancer SPORE projects, investigators and participants. Functions provided by this core include development of experimental designs, data quality control, statistical analysis and interpretation of findings, and collaboration on presentation of results. To achieve these functions, the core director and core biostatisticians are constantly available to investigators, and are in regular contact with the project and pilot project leaders. The primary objectives of the Biostatistics Core are: 1. To provide study design and review all laboratory, animal and clinical studies including feasibility assessment, power analysis and sample size estimation. 2. To collaborate in projects data analysis, interpretation of results, and the writing of final study reports and manuscripts. 3. To work with Clinical Core, Imaging Core and Tissue Core in the development of research project database, to maintain data quality control and to ensure timely data capture. 4. To develop and evaluate statistical methods for experimental design and data analysis. The Biostatistics Core support is required in all Breast Cancer SPORE studies. Core personnel have worked and will continue to work closely with project leaders for assuring that Core provides state-of the-art statistical support.